English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Tools annual

Global: Zendy Free Plan

Global: Zendy Tools monthly

Global: Zendy Plus monthly

Using a large set of XMM-Newton observations we searched for long termspectral and flux variability of the isolated neutron star RX J1856.5-3754 inthe time interval from April 2002 to October 2011. This is the brightest andmost extensively observed source of a small group of nearby, thermally emittingisolated neutron stars, of which at least one member (RX J0720.4-3125, Hohle etal., 2010) has shown long term variability. A detailed analysis of the dataobtained with the EPIC-pn camera in the 0.15-1.2 keV energy range reveals smallvariations in the temperature derived with a single blackbody fit (of the orderof 1% around kT^inf \sim 61 eV). Such variations are correlated with theposition of the source on the detector and can be ascribed to an instrumentaleffect, most likely a spatial dependence of the channel to energy relation. Forthe sampled instrumental coordinates, we quantify this effect as variations of\sim 4% and \sim 15 eV in the gain slope and offset, respectively. Selectingonly a homogeneous subset of observations, with the source imaged at the samedetector position, we find no evidence for spectral or flux variations of RXJ1856.5-3754 from March 2005 to present-day, with limits of Delta kT^inf < 0.5%and Delta f_X < 3% (0.15-1.2 keV), with 3sigma confidence. A slightly highertemperature (kT^inf \sim 61.5 eV, compared to kT^\inf \sim 61 eV) was insteadmeasured in April 2002. If this difference is not of instrumental origin, itimplies a rate of variation \sim -0.15 eV yr^-1 between April 2002 and March2005. The high-statistics spectrum from the selected observations is bestfitted with the sum of two blackbody models, with temperatures kT_h^inf =62.4_{-0.4}^{+0.6} eV and kT_s^\inf = 38.9_{-2.9}^{+4.9} eV, which account forthe flux seen in the optical band. No significant spectral features aredetected, with upper limits of 6 eV on their equivalent width.

Spectral monitoring of RX J1856.5-3754 with XMM-Newton. Analysis of EPIC-pn data